This invention relates generally to an electrophotographic printing machine, and more particularly concerns a substrate feeding system for feeding substrates from a stack along a predetermined path.
In modern high speed sheet processing machines such as printers, sorters, collators, reproduction machines, etc., multi-feeding of sheets can seriously impair operation of the machine. Numerous devices such as impact/paddle feeders of the type disclosed in U.S. Pat. No. 3,630,516, have been employed to minimize the possibility of mis-feeds or multi-feeds.
The aforementioned impact feeders or "inertia feeders" have been employed in top sheet feed devices in an attempt to overcome intersheet friction and assure positive feeding of sheets by jarring or impacting the sheet to be fed and the adjacent sheets. However, in impacting sheets, there is a tendency for the impacting device to jam the sheet to be fed into tighter engagement with the remainder of the sheets in the stack, thereby obviating the benefits obtained in attempting to impact the sheet in the feed direction, off from the remainder of the sheets in the stack. As an improvement, the present top feeder uses combined air jet and air foil shape to lift the top sheet in a stack away from the remainder of the stack before applying an impact feeding mechanism to the stack.